Is it OK to have a boyfriend 4 years younger than me?

I'm 17 and I've been good friends all my life with a boy living next door because I'm a bit of a tomboy so we have a lot in common. Recently I can't help but notice he is quickly growing up to be such a little hottie, but the problem is he is almost 14 years old. Is it OK to have a boyfriend 4 years younger than me, or should I try to ignore my feelings and just stay friends?